Upon attaining revered with The Oracles faction in Sholazar Basin, players can purchase a [Mysterious Egg]. Because it's unique, only one egg can be "incubated" at a time. After three days, the egg becomes lootable as a [Cracked Egg]. Possible loot includes [Aged Yolk], a Green Proto-Drake mount, or one of four vanity pets:

I got this pet after a few eggs, I really like it. If you are trying to get this pet, you will have luck and I bet you will get a lot of them. I gave them to my alts and sisters toons and have been AH ing them.